Document Detail

Morphological and electrophysiological study on the inferior nodal extension and transitional cellular band in the rabbit atrioventricular junctional area.
MedLine Citation:
PMID:  15109444     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Advances in catheter ablation procedures for the treatment of supraventricular arrhythmias have created the need to understand better the morphological and electrophysiological characteristics of the inferior nodal extension (INE) and transitional cellular band (TCB) in the atrioventricular (AV) junctional area. METHODS: Firstly, we observed the histological features of 10 rabbit AV junctional areas by serial sections under light microscopy. Then we recorded the action potentials (APs) of transitional cells (TCs) in the INE, TCBs, AV node, and ordinary right atrial myocytes from the AV junctional area of 30 rabbits using standard intracellular microeletrode techniques. RESULTS: Under light microscopy, the INE appeared to be mostly composed of transitional cells linking upward to the AV node. Four smaller TCBs originated in the orifice of the coronary sinus, the region between the septal leaflet of the tricuspid valve and the coronary sinus, the inferior wall of the left atrium, and the superior interatrial septum, respectively, all linking to the INE or the AV node. Compared with ordinary atrial myocytes, the AP of the TCs in both the INE and the TCBs had a spontaneous phase 4 depolarization (not present in ordinary atrial myocytes), with a less negative maximum diastolic potential, a smaller amplitude, a slower maximum velocity of AP upstroke, and a longer action potential duration at 50% repolarization (APD50) and at 30% repolarization (APD30). The AP characteristics of these TCs were similar to those of the AV node, except that the velocities of the phase 4 spontaneous depolarization were slower and their action potential durations at 90% repolarization (APD90) were shorter. Moreover, APD50 and APD30 of the TCs of the TCBs were shorter than in the case of TCs of the AV node. CONCLUSIONS: The TCs of the INE and TCBs are similar to slow response automatic cells. They provide a substrate for slow pathway conduction. In addition, repolarization heterogeneity exists in the AV junctional area.
Song-Mei Xie; Xiao-Lin Niu; Er-Dan Dong; Ke-Xin Du; Feng-Dong Ling
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Chinese medical journal     Volume:  117     ISSN:  0366-6999     ISO Abbreviation:  Chin. Med. J.     Publication Date:  2004 Apr 
Date Detail:
Created Date:  2004-04-27     Completed Date:  2004-07-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7513795     Medline TA:  Chin Med J (Engl)     Country:  China    
Other Details:
Languages:  eng     Pagination:  532-7     Citation Subset:  IM    
Department of Cardiology, Second Hospital, College of Medicine, Xi'an Jiaotong University, Xi'an 710004, China.
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MeSH Terms
Action Potentials
Atrioventricular Node / cytology*,  physiology

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